Toning shoe employing a bifurcated return port

Abstract

An electrostatic recorder or copier having a toning shoe that includes a plurality of fluid supply channels in a bifurcation means for separating fluids, to avoid back pressure in the toning shoe. The bifurcation means substantially separates a flow of return air from a flow of return toner in the toning shoe by defining a plurality of fluid return channels. The electrostatic recorder or copier also includes a backing support spaced apart from the applicator so as to flexibly retain a recording medium in close proximity to a toning surface of the toning shoe.

We claim: 
     
       1. A toning shoe for an electrostatic recorder or copier comprising: a toning member having a toning surface positioned to face a recording medium having a first major surface bearing a latent image and an opposed second major surface, said toning member having a first side and a second side, spaced apart from and parallel to said first side,   an adjacent member, proximate to and spaced apart from said first side, defining a fluid applicator port therebetween;   a knife edge, positioned proximate to said second side, and spaced apart from said toning member, to remove excess toner from said first major surface of said recording medium;   a first peripheral member disposed on a side of said knife edge opposite to said toning member, said first peripheral member being spaced apart from said knife edge, defining a first major fluid channel therebetween;   a second peripheral member spaced apart from said adjacent member, defining a second major fluid channel therebetween; and   a bifurcation means, disposed between said knife edge and said toning member, for separating a fluid flow, said knife edge and said bifurcation means defining a first fluid return channel therebetween with said toning member and said bifurcation means defining a second fluid return channel therebetween.   
     
     
       2. The toning shoe as recited in claim 1 wherein said toning surface is positioned to be spaced apart from said first major surface a distance, with a width of said second fluid return channel being less than said distance to prevent accumulation of toner on said toning surface during operation. 
     
     
       3. The toning shoe as recited in claim 1 further including a means for placing said first and second major fluid channels in fluid communication with each other. 
     
     
       4. A toner system for applying toner to the surface of a recording medium containing a latent electrostatic image comprising: a toning shoe including a toning member with a surface in fluid communication with a recording medium having a first major surface bearing a latent image and an opposed second major surface, said toning surface facing the first major surface and including a bifurcation means for separating a fluid flow, said bifurcation means defining a first fluid return channel and a second fluid return channel; said toning shoe including a major fluid channel and an applicator port;   a cross member spaced apart from said toning surface, said cross member extending across said applicator to position said recording medium a predefined distance from said toning surface; and   air supply means for directing air into said toning shoe, wherein air exits said major fluid channel to confine toner to said toning surface, toner exits said applicator port to tone said first major surface with excess toner moving adjacent to said toning surface to enter said second fluid return channel and air enters through said first fluid return channel.   
     
     
       5. The system as recited in claim 4 wherein said toning member is spaced apart from said first major surface a distance, with a width of said second fluid return channel being less than said distance to prevent accumulation of toner on said toning surface during operation. 
     
     
       6. The system as recited in claim 5 further including a vise means, connected to said cross member, for providing a variable clamping force to said recording medium. 
     
     
       7. The system as recited in claim 6 wherein said vise means provides said clamping force in response to fluid pressures. 
     
     
       8. The system as recited in claim 6 wherein said vise means includes an elastic bladder. 
     
     
       9. The system as recited in claim 6 wherein the vise means includes a metal surface facing the toning surface to conform to the profile of the toning surface. 
     
     
       10. The system as recited in claim 7 wherein the vise means includes a plurality of metal sheets facing the toning surface to conform to the profile of the toning surface. 
     
     
       11. The system as recited in claim 8 wherein said bladder is formed from an elastic material selected from the group consisting of neoprene or buna-N and includes an electrically grounded electrode facing said toning surface.